The prior art contains a number of self-drilling fasteners adapted to pierce and fasten joints where no pretapped holes have been provided. Such prior art fasteners tend to fall into one of two categories. The first category is one in which the fastener is provided with an end resembling a drill bit, the threads of the fastener beginning above or behind the drill bit end. The effect of providing such a drill bit end on the fastener is to furnish the fastener with one or more chisel edges which in effect cut and lift the material being removed for the entry of the fastener.
The second category of prior art fastener is one in which the threads or portions of the threads extend substantially down to the entering point, but in which the end of the fastener adjacent the point is provided with grooves or flutes adapted essentially to ream out a hole into which the fastener may enter.
Both of the foregoing categories of prior art fastener tend to be somewhat expensive to manufacture, due to the intricate recesses, grooves, chisel edges, etc. which must be provided.
It is therefore an aspect of this invention to provide a self-drilling fastener capable of meeting the standard criteria established for such fasteners, but which tends to be less expensive to manufacture than the prior art fasteners. It is also an aspect of this invention to provide a method for manufacturing such a self-drilling fastener.